34 TYPES OF ANIMAL LIFE 



thought to be most nearly approached by the lemurs, but 

 the advance of anatomical knowledge hardly favours that 

 view. Such resemblance is mainly due to the formation 

 of the extremities. Lemurs, with one exception, certainly 

 have opposable thumbs and great toes to both hands and 

 feet ; but opossums have feet with opposable great toes, 

 and yet no one supposes that there is even the faintest 

 special affinity between an ape and an opossum. In 

 brain structure and in the more intimate processes of 

 reproduction (generally deemed a valuable test of affinity) 

 the apes and lemurs stand far apart; and on the principles 

 of evolution we are convinced that there can be no close 

 relationship between them, although it has been hastily 

 assumed that lemurs were the direct ancestors of apes. 

 Apes, in the present day, stand as it were on a sort of 

 zoological island, and we have no clear evidence indicating 

 from what neighbouring strand they may be conceived 

 to have entered upon it. Their origin thus still remains 

 wrapped in mystery. Nor is it clear that the apes of the 

 New World and those of the Old ever had any ape 

 ancestors common to both. Possibly further discoveries 

 in the Eocene deposits of North America (which are 

 such veritable treasure-houses of relics of ancient 

 life) will reveal to us the past existence of tran- 

 sitional forms between the monkeys of America and of 

 Asia and Africa; but, in spite of all that has been 

 published, this has not, to our minds, been done, and 

 we think it quite possible that these two families have 

 had different origins, and have come to resemble each 

 other independently. The possibility of " the indepen- 

 dent origin of similar structures" is a doctrine we main- 

 tained in the first work we ever published, and increased 

 knowledge and experience has more and more convinced 

 us we were right in maintaining it. But whether the 



